Silicone waxes are well known and are frequently used as lubricants, mold release agents, and internal lubricants for plastics, for example. These products also have anti-blocking properties, and are also used as fiber lubricants and water repellants. These waxes, which may be either hard or soft, may also be emulsified, facilitating the use of the silicone wax in the industrial environment.
Emulsions are mixtures of two liquids in which microscopic droplets of one liquid are intermixed with another liquid. An emulsifying agent is provided to maintain the emulsion. Conventional wax emulsions are generally prepared by emulsifying wax-like materials, meltable solids, in water. These waxes can include paraffin, microcrystalline waxes, vegetable waxes, mineral waxes and synthetic waxes such as polyethylene or polypropylene based products.
There are two commonly used methods of making wax emulsions. The first is mechanical emulsification, a technique applicable to non-functional waxes. Mechanical emulsification typically requires high-power mixers such as homogenizers or colloid mills.
The second method utilizes waxes containing carboxylic acid groups and simple mechanical stirring. Waxes are combined with emulsifiers then added as a melt to hot water containing an alkaline additive, such as potassium hydroxide, alkanolamine, ammonia, etc. Simple stirring of this mixture is sufficient to form a stable emulsion. Waxes used in these emulsions possess acid groups which are introduced by an oxidation process, or, in the case of some polyethylene waxes, by copolymerizing acid functional monomers with ethylene.
Silicone wax emulsions, because of their methylpolysiloxane backbone and the ability to include dimethylsiloxy groups in a silicone wax polymer, offer better water repelling and mold-release performance than their conventional organic wax counterparts. It would be highly desirable to produce silicone wax emulsions by the second method, substituting carboxylic acid functional silicone waxes for conventional hydrocarbon waxes, thereby achieving the improved characteristics of silicone wax emulsions, along with a simplified means of producing these emulsions.